The subject invention is directed to the art of metal bending and, more particularly, to an improved apparatus for bending metal tubes and pipes.
The invention is particularly suited for bending large diameter, thin through thick-walled pipes and tubes and will be described with reference thereto. As will become apparent, however, the invention has unique attributes for incorporation in a variety of tube bending machines used for many different types and sizes of tubular goods.
The bending of pipes and tubes using a rotatably mounted, drum-type bending shoe and cooperating support rollers is well known and has been an accepted and widely used method of tube bending for a significant period of time. A bending apparatus of this general type is shown and described in U.S. Pat. No. 3,949,584, issued Apr. 13, 1976 and entitled "Bending Apparatus Having a Roller Support Unit for E.M.T., Conduit and Thin Walled Tubing".
Typically, tube bending apparatus of this type has been used for lighter walled tubing and conduit but has not been particularly adapted for heavy-walled, large diameter pipe and tubes. Additionally, with benders of the type under consideration, it has been difficult to bend heavy-walled pipes and tubes without causing the tube cross section in the area of the bend to assume an oval or flattened shape. Machines used for field bending of thin-walled tubing, likewise, often produce a "wrinkled" distortion in the area of the bend. Moreover, it has been difficult to control and precisely produce a bend of a desired angle. The need for such a bender capable of handling heavy through thin-walled tubes has been an ongoing problem.